With the Maryland General Assembly looking toward two possible special sessions this year, some lawmakers are calling for an expanded agenda to address long-term transportation funding.

Gov. Martin O'Malley and House leaders have made clear that they want to devote a May special session exclusively to passing new revenue and income-tax increases to supplement a $35.4-billion budget that currently includes more than $500 million in cuts because of the assembly’s failure to pass a revenue package during the regular session. Mr. O'Malley, a Democrat, said Tuesday that is his only priority for a May special session.

Other proposals would have to wait for a possible August special session, he said, including a bill to let voters decide whether to build a casino in Prince George’s County and allow the state’s current slots casinos to add table games.

Splitting the issues, the governor said, would help avoid a repeat of the regular session’s final days, when the governor and House leaders accused the Senate of holding up the budget to try to force House passage of the gambling bill.

The governor can state his preferences, but the course for both special sessions would be decided largely by legislative leaders, ranging from the House speaker and Senate president down to committee and county-delegation chairs.

Mr. O'Malley’s representatives say he has given little thought to whether a second session could include issues beyond gambling — including his failed proposals to implement offshore wind energy and increase the gas or sales tax to fund transportation projects.

Some Democratic lawmakers say they want to explore adding hundreds of millions in new revenues to the state’s Transportation Trust Fund, which relies heavily on gas-tax revenue and is the sole funding source for most road and transit projects.

The TTF, which is separate from the state’s general fund, has been diminished in recent years by decreasing fuel consumption and heavy borrowing from it for non-transportation purposes.

“After fixing the budget, I think transportation should definitely be the number-one issue in the state,” said Delegate Eric G. Luedtke, Montgomery Democrat. “I think most reasonable observers would agree that transportation improvements are needed.”

Sen. James C. Rosapepe, Prince George’s Democrat, said he and Delegate Brian J. Feldman, Montgomery Democrat, will introduce a constitutional amendment in the second special session that could pave the way for a statewide vote on a transportation funding package as soon as 2014.

“I think people are intrigued,” Mr. Rosapepe said. “Given the failure of the traditional approaches over many years, pretty much everybody I’ve talked to is interested in it.”

Proposals this year to replenish the TTF died largely because of public outcry and high gas prices, but some lawmakers say avoiding the issue will only make things worse.

Sen. Richard S. Madaleno Jr. said he thinks the summer would be an ideal time to pass a gas tax because gas prices that typically rise each spring during the assembly’s regular session often stabilize by midsummer.

“We’re always going to be caught in a problem of having our session coincide every year with increasing gas prices,” said Mr. Madaleno, Montgomery Democrat. “We’re never going to make progress unless we deal with this issue during a different time of year when prices are more rational.”

While Democrats say more funds are needed for aging infrastructure, Republicans disagree and say the state needs to better protect the TTF from outside borrowing and perhaps look for extra funding from jurisdictions with higher transit usage and needs.